1.

The solution of the differential equation `(1+xy)xdy+(1-xy)ydx=0` ,isA. `(1)/(xy)+log((y)/(x))=C`B. `-xy+log((y)/(x))=C`C. `-(1)/(xy)+log((y)/(x))=C`D. `-(1)/(xy)+log((x)/(y))=C`

Answer» Correct Answer - C
The given equation can be written as
`(xdy+ydx)+xy(xdy-ydx)=0`
`rArr" "d(xy)+xy(xdy-ydx)=0`
`rArr" "(d(xy))/((xy)^(2))+(xdy-ydx)/(xy)=0`
`rArr" "(d(xy))/((xy)^(2))+(dy)/(y)-(dx)/(x)=0`
`rArr" "(d(x))/((xy)^(2))+d(logy)-d(logx)=0`
`rArr" "(d(xy))/((xy)^(2))+d(logy-logx)=0`
`rArr" "(d(xy))/((xy)^(2))+dlog((y)/(x))=0`
On integrating, we get
`-(1)/(xy)+log((y)/(x))=C` as the required solution.


Discussion

No Comment Found

Related InterviewSolutions